ST7571 Sitronix Technology, ST7571 Datasheet - Page 23

• Manufacturer Part Number: ST7571
• Description: 4 Gray Scale Dot Matrix LCD Controller/Driver
• Manufacturer: Sitronix Technology

www.DataSheet4U.com
ST7571
7.3 LCD DISPLAY CIRCUITS
Oscillator
This is on-chip Oscillator without external resistor. When the internal oscillator is used, this pin must connect to VDD1; when
the external oscillator is used, this pin could be input pin. This oscillator signal is used in the voltage converter and display
timing generation circuit.
Display Timing Generator Circuit
This circuit generates some signals to be used for displaying LCD. The display clock, CL (internal), generated by oscillation
clock, generates the clock for the line counter and the signal for the display data latch. The line address of on-chip RAM is
generated in synchronization with the display clock and the display data latch circuit latches the 128-bit display data in
synchronization with the display clock. The display data, which is read to the LCD driver, is completely independent of the
access to the display data RAM from the microprocessor. The display clock generates an LCD AC signal (FR) which
enables the LCD driver to make an AC drive waveform, and also generates an internal common timing signal and start
signal to the common driver. The frame signal or the line signal changes the M by setting internal instruction. Driving
waveform and internal timing signal are shown in Fig. 13.
Ver 1.5a
FR(Internal)
CL(Internal)
Frame
COM10
COM0
SEGn
127
128
Fig. 14 N-Line Inversion Driving Waveform (N=5,Duty Ratio=1/129)
0
1
2 3 4 5 6 7 8 9
Fig. 13 Frame AC Driving Waveform (Duty Ratio: 1/129)
10 11
23/76
120
121
122
123
124
125
126
127
128
0
1
2
3 4
2009/7/21